Check weighing systems are used for example in quality control of products on a production line to ensure that each container (or other package) contains a required amount of product. For example check weighing is used by the pharmaceuticals industry for monitoring and regulation of the amount of a drug sealed in glass vials. The drug weight can be as small as a fraction of a gram, and must be weighed with an accuracy of a few percent or better, in a vial weighing tens of grams and at a rate of several weighings per second.
International patent application publication WO 99/67606 discloses a check weighing apparatus and method for check weighing products in such applications using NMR.